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MRLs are substance specific estimates, which are intended to serve as screening levels, are used by ATSDR health assessors and other responders to identify contaminants and potential health effects that may be of concern at hazardous waste sites.

The international and national regulations, advisories, and guidelines regarding ester flame retardants in air, water, and other media are summarized in Table 8-1.

ATSDR has derived an intermediate-duration oral MRL of 0.6 mg/kg/day for TCEP based on an increased incidence of brain lesions in female Fischer-344 rats dosed by gavage 5 days/week for 16 weeks (NTP 1991a). The MRL was derived using benchmark modeling of incidence data for brain lesions in female rats. The predicted dose associated with a 10% extra risk (BMD10) for brain lesions was

143.41 mg/kg/day; the lower 95% confidence limit on this dose (BMDL10) was 85.07 mg/kg/day. An uncertainty factor of 100 was used (10 for animal to human extrapolation and 10 for human variability).

ATSDR has derived a chronic-duration oral MRL of 0.2 mg/kg/day for TCEP based on an increased incidence of renal tubule epithelial hyperplasia in female Fischer-344 rats dosed by gavage 5 days/week for 2 years (NTP 1991a). The MRL was derived using benchmark modeling of incidence data for renal lesions in female rats. The BMD10 for renal lesions was 48.00 mg/kg/day; the BMDL10 was 32.82 mg/kg/day. An uncertainty factor of 100 was used (10 for animal to human extrapolation and 10 for human variability).

ATSDR has derived an acute-duration oral MRL of 1.1 mg/kg/day for TnBP based on decreased body weight gain in Wistar rats during pregnancy (Noda et al. 1994). The MRL was derived using benchmark

modeling of the decrease in body weight gain. The BMD1SD was 130.32 mg/kg/day; the corresponding

BMDL1SD was 111.47 mg/kg/day. An uncertainty factor of 100 was used (10 for animal to human extrapolation and 10 for human variability).

ATSDR has derived an intermediate-duration oral MRL of 0.08 mg/kg/day for TnBP based on an increased incidence of urinary bladder hyperplasia in male Sprague-Dawley rats dosed via the diet for 10 weeks (Arnold et al. 1997). The MRL was derived using benchmark modeling of incidence data for urinary bladder lesions in male rats. The BMD10 for urinary bladder lesions was 19.74 mg/kg/day; the

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Table 8-1. Regulations, Advisories, and Guidelines Phosphate Ester Flame Retardants

Agency Description Information Reference INTERNATIONAL Guidelines: IARC Carcinogenicity classification Group 3a IARC 2009 Tris-(2-chloroethyl)-phosphate WHO Air quality guidelines No WHO 2000 Drinking water quality guidelines No WHO 2006 NATIONAL Regulations and Guidelines: a. Air ACGIH TLV (8-hour TWA) ACGIH 2008 Tributyl phosphate 2.5 mg/m3 (0.19 ppm) Triphenyl phosphate 3.0 mg/m3 (0.22 ppm) TLV Basis Tributyl phosphate Nausea, headache, eye and upper respiratory irritation Triphenyl phosphate Cholinesterase inhibitor AIHA ERPG values No AIHA 2008 EPA AEGL values No EPA 2009a Hazardous air pollutant No EPA 2009b 42 USC 7412 NIOSH REL (10-hour TWA) NIOSH 2005b Tributyl phosphate 2.5 mg/m3 (0.19 ppm) Triphenyl phosphate 3.0 mg/m3 (0.22 ppm) IDLH Tributyl phosphate 327 mg/m3 (30 ppm) Triphenyl phosphate 1,000 mg/m3 (75 ppm) Target organs Tributyl phosphate Eyes, skin, and respiratory system Triphenyl phosphate Blood and peripheral nervous system OSHA PEL (8-hour TWA) for general industry OSHA 2009 Tributyl phosphate 5.0 mg/m3 (0.46 ppm) 29 CFR 1910.1000, Table Z-1 Triphenyl phosphate 3.0 mg/m3 (0.22 ppm)

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Table 8-1. Regulations, Advisories, and Guidelines Phosphate Ester Flame Retardants

Agency Description Information Reference NATIONAL (cont.) b. Water EPA Drinking water standards and health No EPA 2006a advisories National primary drinking water No EPA 2003 standards National recommended water quality No EPA 2006b criteria c. Food FDA EAFUSb No FDA 2008 d. Other ACGIH Carcinogenicity classification ACGIH 2008 Tributyl phosphate No Triphenyl phosphate A4c EPA Inert ingredients are permitted for use in EPA 2009c nonfood use pesticide products Tributyl phosphate, tributoxyethyl Yes phosphate, and triphenyl phosphate Inert ingredients are no longer EPA 1998b permitted for use in nonfood use 63 FR 34834 pesticide products Tricresyl phosphate Yes Carcinogenicity classification No IRIS 2009 RfC No RfD No MTL EPA 2009 Triphenyl phosphate Yesd Tricresyl phosphate Yesd Tri-(2-chloroisopropyl) phosphate Yese Tris-(2-chloroethyl)-phosphate Yese Superfund, emergency planning, and community right-to-know Designated CERCLA hazardous No EPA 2009d substance 40 CFR 302.4 Effective date of toxic chemical No EPA 2009e release reporting 40 CFR 372.65

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Table 8-1. Regulations, Advisories, and Guidelines Phosphate Ester Flame Retardants

Agency Description Information Reference NATIONAL (cont.) EPA TSCA chemical lists and reporting EPA 2009f periods 40 CFR 712.30 Tributyl phosphate, triisobutyl phosphate, and tributoxyethyl phosphate Effective date 10/29/1990 Reporting date 12/27/1990 TSCA health and safety data reporting EPA 2009g Tributyl phosphate 40 CFR 716.120 Effective date 06/18/1986 Sunset date 06/18/1996 Tricresyl phosphate EPA 2009g Effective date 10/04/1982 40 CFR 716.120 Sunset date 10/04/1992 Trisobutyl phosphate Effective date 10/29/1990 Sunset date 11/09/1993 Tributoxyethyl phosphate Effective date 10/29/1990 Sunset date 12/19/1995 Triphenyl phosphate Effective date 10/04/1982 Sunset date 10/04/1992 TSCA chemical lists and reporting EPA 2009f periods 40 CFR 712.30 Tri-(2-chloroisopropyl) phosphate and tris-(2-chloroethyl)-phosphate Effective date 12/16/1988 Sunset date 11/09/1993 Tris(1,3-dichloro-2-propyl) phosphate Effective date 12/16/1988 Sunset date 12/19/1995

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Table 8-1. Regulations, Advisories, and Guidelines Phosphate Ester Flame Retardants

Agency Description Information Reference NATIONAL (cont.) NTP Carcinogenicity classification No data NTP 2005 Nominated for in-depth toxicological Tricresyl phosphate NTP 2011 evaluation aGroup 3: not classifiable as to carcinogenicity to humans bThe EAFUS list of substances contains ingredients added directly to food that FDA has either approved as food additives or listed or affirmed as GRAS. cA4: not classifiable as a human carcinogen dTriphenyl phosphate and tricresyl phosphate were added to the MTL in 1992 and the testing action development is underway. The testing needs include health effects, ecological effects, and chemical fate. eTri-(2-chloroisopropyl) phosphate and tris-(2-chloroethyl)-phosphate were added to the MTL in 1992 and the chemical testing program is underway.

ACGIH = American Conference of Governmental Industrial Hygienists; AEGL = acute exposure guideline levels; AIHA = American Industrial Hygiene Association; CERCLA = Comprehensive Environmental Response, Compensation, and Liability Act; CFR = Code of Federal Regulations; EAFUS = Everything Added to Food in the United States; EPA = Environmental Protection Agency; ERPG = emergency response planning guidelines; FDA = Food and Drug Administration; FR = Federal Register; GRAS = Generally Recognized As Safe; IARC = International Agency for Research on Cancer; IDLH = immediately dangerous to life or health; IRIS = Integrated Risk Information System; MTL = Master Testing List; NIOSH = National Institute for Occupational Safety and Health; NTP = National Program; OSHA = Occupational Safety and Health Administration; PEL = permissible exposure limit; REL = recommended exposure limit; RfC = inhalation reference concentration; RfD = oral reference dose; TLV = threshold limit values; TSCA = Toxic Substances Control Act; TWA = time-weighted average; USC = United States Code; WHO = World Health Organization

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BMDL10 was 8.03 mg/kg/day. An uncertainty factor of 100 was used (10 for animal to human extrapolation and 10 for human variability).

ATSDR has adopted the intermediate-duration oral MRL of 0.08 mg/kg/day for TnBP also as the chronic- duration oral MRL for TnBP. A detailed explanation can be found in Section 2.3.

ATSDR has derived an acute-duration oral MRL of 4.8 mg/kg/day for TBEP based on decreased body weight gain in CD rats during Gd 6–15 (Monsanto Co. 1985b). The MRL was derived using benchmark modeling of the decrease in body weight gain. The BMD1SD was 824.97 mg/kg/day; the corresponding

BMDL1SD was 477.25 mg/kg/day. An uncertainty factor of 100 was used (10 for animal to human extrapolation and 10 for human variability).

ATSDR has derived an intermediate-duration oral MRL of 0.09 mg/kg/day for TBEP based on an increased incidence of periportal hepatocyte vacuolization in male Sprague-Dawley rats dosed via the diet for 18 weeks (Reyna and Thake 1987a). The MRL was derived using benchmark modeling of incidence data for hepatocyte vacuolization in male rats. The BMD10 for hepatocyte vacuolization was

22.02 mg/kg/day; the BMDL10 was 8.88 mg/kg/day. An uncertainty factor of 100 was used (10 for animal to human extrapolation and 10 for human variability).

ATSDR has derived an intermediate-duration oral MRL of 0.05 mg/kg/day for TDCP based on increased absolute kidney weight in male Sprague-Dawley rats dosed via the diet for 12 months (Stauffer Chemical Co. 1981a). The MRL was derived using benchmark modeling of the increase in kidney weight. The

BMD1SD was 13.36 mg/kg/day; the corresponding BMDL1SD was 4.69 mg/kg/day. An uncertainty factor of 100 was used (10 for animal to human extrapolation and 10 for human variability).

ATSDR has derived a chronic-duration oral MRL of 0.02 mg/kg/day for TDCP based on an increased incidence of renal tubular epithelial hyperplasia in male Sprague-Dawley rats dosed via the diet for 2 years (Stauffer Chemical Co. 1981a). The MRL was derived using benchmark modeling of incidence

data for renal lesions in male rats. The BMD10 for renal tubular hyperplasia was 2.60 mg/kg/day; the

lower 95% confidence limit on this dose (BMDL10) was 1.94 mg/kg/day. An uncertainty factor of 100 was used (10 for animal to human extrapolation and 10 for human variability).

ATSDR has derived an intermediate-duration oral MRL of 0.04 mg/kg/day for TCP based on an increased incidence of hyperplasia of the interstitial cell in the ovary in female F344/N rats dosed via the diet for

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3 months (NTP 1994). The MRL was derived using benchmark modeling of incidence data for ovarian

lesions. The BMD10 for ovarian lesions was 6.21 mg/kg/day; the lower 95% confidence limit on this dose

(BMDL10) was 3.72 mg/kg/day. An uncertainty factor of 100 was used (10 for animal to human extrapolation and 10 for human variability).

ATSDR has derived a chronic-duration oral MRL of 0.02 mg/kg/day for TCP based on an increased incidence of hyperplasia of the interstitial cell in the ovary in female F344/N rats dosed via the diet for 15 months (NTP 1994). The MRL was derived using benchmark modeling of incidence data for ovarian lesions. The BMD10 for ovarian lesions was 5.22 mg/kg/day; the lower 95% confidence limit on this dose

(BMDL10) was 2.12 mg/kg/day. An uncertainty factor of 100 was used (10 for animal to human extrapolation and 10 for human variability).

EPA (IRIS 2009) has not established an oral reference dose (RfD) or inhalation reference concentration (RfC) for phosphate ester flame retardants.

The International Agency for Research on Cancer (IARC) has classified TCEP as a Group 3 carcinogen (not classifiable as to carcinogenicity to humans) (IARC 2009). The American Conference of Governmental Industrial Hygienists (ACGIH) has classified TPP as an A4 carcinogen (not classifiable as a human carcinogen) (ACGIH 2008). Neither the National Toxicology Program (NTP) nor the EPA has classified the phosphate ester flame retardants discussed in this profile for human carcinogenicity (IRIS 2009; NTP 2005).

OSHA has required employers of workers who are occupationally exposed to TnBP and TPP to institute engineering controls and work practices to reduce and maintain employee exposure at or below permissible exposure limits (PELs) (OSHA 2009). The employer must use engineering and work practice controls to reduce exposures to not exceed 5 and 3 mg/m3 at any time for TnBP and TPP, respectively (OSHA 2009).

Under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), TnBP, TBPE, and TPP are permitted for use in nonfood pesticide products (EPA 2009c).

All of the phosphate ester flame retardants subject of this profile are required under Section 4(a) of the Toxic Substances Control Act (TSCA) to submit copies of health and safety studies (EPA 2009f). TnBP,

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TiBP, and TBEP are required to report production, use, and exposure-related information on chemical substances listed under TSCA (EPA 2009g).